1. Field of the Invention
The present invention generally relates to vehicle simulators and, more particularly, is concerned with realistically simulating to the user the feeling of the vehicle controls and the vehicle ride as it moves within the simulated universe.
2. Background of the Invention
A vehicle simulator can be defined as a system that simulates the operating conditions of a vehicle in an environment. Where the vehicle simulated is an automobile, the vehicle will usually include the typical automobile controls such as a steering wheel, a gear shift, an accelerator pedal, and a brake pedal. Generally, this vehicle will be simulated in an environment which will typically include a road.
Vehicle simulators provide a means to efficiently train operators of a vehicle. The operator of a vehicle can safely learn, from the simulator, how the vehicle will operate in a given set of conditions without actually exposing the operator to any of the risks inherent in real world operation of the vehicle. The experience garnered through making mistakes on a simulator is invaluable when compared to the inherent risks of vehicle damage and operator injury associated with making a driving error in a real-life situation. For example, in a police training application, a student could learn the limits of a police cruiser or guidelines for pursuit, and be tested in these areas without any of the associated risks of real-life training.
In addition to concerns relating to operator safety and vehicle damage, training through actual vehicle operation has other pitfalls. In particular, the cost of instructor time may be prohibitive. Furthermore, a specific vehicle such as a space or underwater vehicle, may simply not be available for training purposes.
To enhance the effectiveness of the training afforded by vehicle simulators, there is a need to ensure that the simulator realistically simulates both the feel of operating the vehicle, as well as realistically simulating the effect of operating the various vehicle controls, in specific situations. Realistically simulating the feel of operating a vehicle includes simulating the feel of the vehicle as it travels in a simulated environment as well as simulating the feel of the various vehicle controls during actual usage.
In automobile simulators the effectiveness of the training given by the simulator would be enhanced if the simulator could translate to the operator the feeling of a wide variety of road surfaces and objects that an automobile is likely to come in contact with. Specifically, there is a need for a system that will generate a wide variety of road feel cues based on where the simulated automobile is within a simulated universe and what the simulated automobile contacts within that universe.
One example of where a prior art simulator has attempted to simulate the feeling of a vehicle operating in an environment is shown in U.S. Pat. No. 4,574,391 to Morishima. Morishima discloses a sound system for a video game, configured for giving a live action feeling to a game involving artillery. This sound system includes several audio speakers mounted around the user's head as well as a low frequency speaker mounted underneath the user's seat. The live action feeling is generated by having the audio speakers generating artillery sound in sequence thereby creating the illusion of the artillery shell approaching and, when the round hits, sending low frequency components of the explosion sound to the low frequency speaker mounted underneath the user's seat. The low frequency speaker then causes the seat to vibrate as a direct result of an explosion sound.
One shortcoming of the system disclosed in Morishima is that the seat vibration and the sound of the explosion are not generated independently. That is, the vibration is a direct result of the low frequency components of the sound of the explosion. Generating physical feedback by transmitting the low frequency component of an associated sound limits such feedback to only sound events having a sufficiently large low frequency component to cause the seat to vibrate. Consequently, the feel of events which occur during the simulation which do not have a large low frequency component cannot be represented to the user. Hence, there is a present need for a system which is capable of simulating a vehicle in a specific environment and, which is capable of providing physical feedback based on a variety of simulated events which are not always accompanied by a sound including a large low frequency component.
In automobile simulators, the effectiveness of the training given by the simulator would be further enhanced if the feel of the brake pedal to the operator closely approximated the feel of an actual brake pedal in an actual car when the brake pedal is depressed. Further, the effect of depressing the brake pedal a given amount in the automobile simulator, as perceived by the operator (or user), should also closely approximate the effect that depressing the brake pedal the same amount has in a real-life automobile.
Many of today's automobiles are equipped with Anti-Lock Brake (ABS) systems. An ABS system is a safety feature added to automobiles to enhance the controllability of automobiles during braking maneuvers. When non-ABS brakes are suddenly applied, or applied with great force, the brakes may lock up and consequently the automobile will often enter into an uncontrollable skid. An automobile tire will skid over pavement when the forward momentum of the automobile exceeds the velocity of the tire, thereby dragging the tire forward over the pavement in a skidding fashion. An ABS braking system acts to prevent such uncontrollable skids by sensing when the tire is being dragged over the pavement, and then decreasing the amount of stopping pressure exerted by the brakes against the wheel by an amount just sufficient to permit the tire to continue to roll over the pavement while still slowing the rotation of the tire. The ABS system will then typically oscillate between increasing and decreasing the amount of braking force exerted against the tire as the ABS system tries to slow the rotational velocity of the tires, while also preventing the brakes from locking up. This oscillation results in a unique, vibratory pulsation of the brake pedal during braking.
Currently, no known vehicle simulators simulate the feel, or the effect, of ABS brakes. However, a person driving an automobile equipped with ABS brakes may become startled when they first experience the feeling of a brake pedal of a vehicle which is equipped with ABS brakes and, as a consequence, stop braking the vehicle when braking is necessary. Hence, the lack of a simulator which will simulate an automobile equipped with ABS brakes represents an additional shortcoming in the prior art relating to driving training simulators.